Electric-lighting system



(No Model.)

B. THOMSON. ELECTRIC LIGHTING SYSTEM.

No. 448,279. Patented Mar. 17, 1891.

INVENTOR.

ATTORNEY na 20.. moYo-umo., wuumrm, u. c.

UNITED STATES PATENT OFFICE.

ELII-IU THOMSON, OF LYNN, MASSACHUSETTS, ASSIGNOR TO THE THOMSON- HOUSTON ELECTRIC COMPANY, OF CONNECTICUT.

ELECTRIC-LIGHTING SYSTEM.

SPECIFICATION forming part of Letters Patent No. 448,279, dated March 17, 1891.

Serial No. 202,843. (No model.)

To aZZ whom it may concern.-

Be it known that I, ELIHU THOMSON, a citizen of the United States, and a resident of Lynn, in the county of Essex and State of Massachusetts, have invented certain new and useful Regulators for Electric Circuits, of which the following is a specification.

My present invention relates to a means of automatically regulating the flow of current to a group of incandescent lights or other translating devices arranged in multiple are upon a line on which the current supplied is of fairly uniform amount, such as an arelight line or a line of high potential supplying a number of such groups in series.

The invention consists, briefly, in the combination of an electro-magnet constructed to move its armature step by step in response to definite changes in the strength of said magnet, and connected to the circuit so as to be in derived connectio11' around the lights or other translating devices, with means whereby the successive movements of the armature introduce resistances of definite amount and equal to the number of lights that may be extinguished by accident or otherwise in the group supplied.

Various constructions for obtaining a stepby-step movement of the armature of the magnet appear in another case filed by me January 9, 1886, Serial No. 190,495, and are made the subject of claims therein.

Figure 1 shows diagrammatically a group of incandescent lamps combined with a magnet and artificial resistances according to my invention. Fig. 2 shows an outline of the magnet-poles. Fig. 3 shows a modification of the magnet-poles and armature. Fig. 4 shows another modification giving the same properties. Fig. 5 shows still another magnetic arrangement having similarproperties. Fig. 0 shows a modification in the grouping of the lamps.

The magnet employed by me has a uniformity of pull through its range of move ment with certain definite energization, except in so far as the shaping or grooving of its polar portions disturbs this uniformity at certain positions in the range of movement and causes the armature to move step by step.

In Fig. 1, a b are connections to a high-potential line or other suitable source of current of electricity for operating a group of electric lights L L in multiple are, the num 5 5 her of lights in the group being such as will utilize the current flowing and each lamp taking a fraction of the current. It is evident that if a light be extinguished the fraction of the current which would have supplied it that resistances be substituted for the unused 6 5 lights, so that the current supplied to each lamp may remain of uniform volume. It is also desirable in case the current in the circuit increases that resistances shall be substituted in multiple with the lights to prevent undue brilliancy, and it is further desirable that such substitution shall take place quickly and by certain definite amounts and not be subject to rapid and quick vibrations or fluctuations,

which show themselves in the light emitted by the lamp as tremor or flickering. To this end I place in derived circuit with the lights an eleetro-magnet K of very high resistance, so as to use only a small portion of the current, which magnet is constructed to have the properties above mentioned-that is to say, its armature A moves in front of its pole with a uniform pull; but the said pole is grooved or is provided with a series of attracting projections arranged so as to give a movement of the armature by jumps or steps, each of which jumps or steps serves to introduce into branch circuit around the group of lamps one of several resistances R R B. This is effected by suitable contacts 0 0, connected to the wire a, and which are carried by the armature-lever L and dip into mercury-cups N, connected to the resistances R R R in the manner shown. The adjustments are made such that when the normal current flows and 9 5 the normal number of lamps in a group is burning the armature A is down; but on the extinguishment, by accident or otherwise, of a lamp the consequent increase in the power of K will cause the first contact at C to I00 dip-that is, the armature A will make one step in its motion. The en'tinguishment of another lamp will cause a similar increase and the armature A will make another step,- dipping another contact, which contactthrows in a resistance equivalent to the lamp, and thus the power of the magnet K is restored to the normal after each. addition. The addition of a light has the opposite effect, cansing the armature A to drop back and take out one by one, as may be needed, of the resistances until the power of K is reestablished at its normal.

The form of magnet-pole suitable for giving to the armature of the magnet a step-bystep movement such that at each step a new contact shall be made in the resistance-varying device, as before described, is shown in Fig. 2..

As will be here seen, the face of the magnet-pole M is provided with a series of transverse grooves, so as to produce a pole having a series of attracting projecting portions before which the armature shall hesitate or tend to comev to rest because of the greater attracting influence opposite such projections than at the depressed portions between them. The same result may be obtained by the employment ofa series of supplemental or subsidiaryattracting portions independent of the core of the electro-magnet itself. Such a construction is illustrated in 3, where a supplemental or secondary body of magnetic material N is shown arranged in proximity to thearmature A, and grooved so as to form a series of attracting projections similar to those shown in Fig. 2 upon the pole-face of the magnet itself. The piece N may be simply a mass of soft iron, or it may be magnetized steel, and its purpose is to exert a slight attractive force on the armature A, which force has defects or faults at certain points V V V V by reason of the grooves or depressions at such points, the result of which is that the armature A, when attracted by the pole M,

hesitates alittle before it crosses the grooves.

In Fig. 4: the arrangement is modified by supplying a small permanently-magnetized bar 0 of slight power, carried on the armature A and coming successively opposite small magnetic bars I I I. A projecting notched surface may be substituted therefor; or the bar 0 may be'of soft iron and the bars I I I be weak, permanent, or electro magnets.

Any of these dispositions will cause a slight hesitancy in the passage of the armature in front of the pole M and it will make its movements step by step. I

In Fig. '5 a similar property is conferred upon a solenoid or axial magnet, the coil of which K is wound in such shape as to attract itscoreA' withapower fairly uniform throughi out the range of movement. The core A,

however, has upon its sides notchesor grooves, which, as it rises, come successively opposite to the steel or soft-iron magnetic portions P P, which gives a slight hesitancy of movement at points between the grooves, and the core moves step by step. Atthe lower part of the figure is also shown another disposition serving a similar purpose, and consisting of small iron projections 0, carried by the core A, between fixed surfaces N S, feebly magnetized and .having faces opposed to the outline of 0 of a wavy or notched form, so as to form a series of attracting projections to tend to hold the piece 0 slightly at several positions during its motion.

Fig. 6 shows how the grouping of lamps may be changed by putting several lights in .each multiple-arc branch, each branch line then containing two or more lamps, as L L In this case the resistance R must of course be equal to. that of the number of lamps used in series, and the magnet K is adjusted asbefore to act onthe rupture or breakage of one net responsive to changes of potential at the terminals of the group and having a step-bystep movement, as described, in combination with artificial resistances and means controlled bythe magnet for introducing said resistanees singly and successively into circuit by the step-by-step movement to compensate for the rupture of sub-circuits containing lamps or other translating devices.

2. The combination, with an electro-magnet, of a series of subsidiary attracting pro jections independent of the magnet-core and systematically disposed, as described, whereby the armature or its equivalent of the magnet may be caused to move step by step or to assume certain definite positions through its range of movement, depending upon the location of the several projections of the series. 3. The combination, with an electro-magnet having a movable core, (if a series of attractin g project-ions extending transversely to the line of 'movementof the core and systematically disposed, as described, whereby the core may be caused to assume certain definite positi'ons in its range of movement, depending upon the location of the several projections 1 of the series.

4. The combination, with the movable core for an electro-magn-et, of a series of attracting projections extending transversely from the side of the core and an armature or piece of magnetic material before which such pro jections successively pass, whereby said core may be caused to move step by step through I its normal range of movement.

Signed at Lynn, in the county of Essex and I State of Massachusetts, this 18th day of May, A. D. 1886. I ELI HU THOMSON,

Witnesses:

W. O. WAKEFIELD, II. KETFI'ELD. 

